The battery packs for portable power tools, outdoor tools, and certain kitchen and domestic appliances usually have several cells disposed in series. Users typically remove the battery packs from the battery charger after completion of the fast charging process, but before sufficient equalizing charge has been provided to the battery for equalizing the capacities of the various cells. Over time, the cell capacities become further out of balance, with some cells becoming significantly lower in capacity relative to the others.
The battery pack is typically usable until the charge in the lower-capacity cells is depleted. Accordingly, the user perceives that the capacity of the battery pack and/or battery life is decreased and may incorrectly attribute this to a "memory" problem. The user may also perceive that the battery pack may be defective.
It is preferable to provide a method and apparatus that enables the user to equalize, or "refresh," the cell capacities, in order to restore battery pack capacity.